The invention relates generally to a system and method for obtaining physiological data measurements and providing certain optically induced treatment regimens, and more particularly to a system and method for optically measuring oximetric information and providing photodynamic therapy or tissue healing therapy through non-intrusive means.
There are numerous instances where oximetric measurements are necessary for the proper treatment of individuals experiencing some form of health crisis. For example, neonates, newborn babies with a birth weight of 1500 grams or less, are in a fragile state immediately after birth and for some time thereafter. Due to their fragility, any disturbance to them could be dangerous, and even life threatening. Neonates must be continually and extensively monitored so that the most efficacious medical regimen may be administered. Most physiological monitoring mechanisms incorporate extensive sensors and cabling which must be attached to the neonate, and such monitoring mechanisms lead to a tension between the need to monitor neonates and the need to disturb them as little as possible.
Two important measurements for neonates include detection of physical movement as a sign of life and estimation of cardiac and cardiopulmonary data, including pulse oximetry. Conventionally, pulse oximetry is often performed through an oximeter which is attached either at the finger or the ear and which measures the absorption of light of two different wavelengths. A pulse oximeter works by passing a beam of red and infrared light through a pulsating capillary bed. The ratio of red to infrared blood light transmitted gives a measure of the oxygen saturation of the blood. The measurements of the two different beams, which have two different wavelengths, usually straddle an isosbestic point, the wavelength at which the molar extinction coefficients are equal, i.e., the point at which the absorption spectra of two species cross each other. As shown in FIG. 1, the two species are oxyhemoglobin (“Oxy”) and deoxyhemoglobin (“Deoxy”), and their molar extinction coefficients are equal, namely the isosbestic point 10, at a wavelength of about 805 nanometers. For neonates, use of a finger or ear oximeter for obtaining pulse oximetry is disturbing.
Another conventional approach for obtaining pulse oximetry is found in U.S. Pat. No. 6,470,200, in which is disclosed a pacifier with an oximetric sensor. The sensor may be optionally equipped with wireless communications, for wirelessly reporting the measured oximetric data. This approach is not suitable for neonates, as they are not yet developed fully to the stage of being able to reliably handle a pacifier.
Another example of when oximetric monitoring is important is during a surgical procedure under a general anesthetic. Conventional anesthetic mechanisms are closed systems that re-circulate the anesthetic. Known anesthetic mechanisms utilize a canister that includes a carbon dioxide scrubber through which the expired outflow from the patient, including the anesthetic and expired air, is recycled. The carbon dioxide scrubber removes the carbon dioxide from the outflow. One known anesthetic mechanism uses Baralyme® as the scrubbing material and Sevoflurane™ as the anesthetic. Carbon dioxide scrubbers have an initial level of moisture, and through use become less moist. If a carbon dioxide scrubber becomes desiccated, a build up of carbon monoxide may occur in the scrubber, and that carbon monoxide may be added to the outflow. Carbon monoxide has an affinity for hemoglobin that is more than two hundred times greater than that for either oxygen or carbon dioxide, and the introduction of carbon monoxide in the outflow can lead to carboxyhemoglobin in levels that are dangerous to the patient.
Additionally, there are certain medical treatment regimens that are optically induced, namely that utilize light in a somewhat catalytic way. For example, light may be used to activate light-sensitive chemotherapy drugs. Also, light may be used to stimulate tissue growth and regeneration.
There exists a need for an efficacious methodology for gathering physiological data and for performing certain optically induced treatment regimens that is less disturbing to the patient.